In the art of printing machines for securities, such as banknotes, checks and other similar objects, an important feature which is printed on said securities is a serial number. For example, each printed banknote typically receives a unique combination of numbers and characters building the serial number of the banknote.
Many numbering processes have been developed in the art. For example, U.S. Pat. No. 4,677,910, the content of which is incorporated by reference in the present application, discloses a process and an apparatus for processing security prints arranged in lines and columns on a carrier in the form of webs or sheets. In this particular example, the printed carriers pass, in succession, by a reading instrument which detects the positions of defective prints identified by a mark and feeds the position to a computer for storage, a cancellation printer controlled by the computer which provides the defective prints with a cancellation print, and a numbering machine. The numbering mechanisms of this numbering machine are actuated by the computer in such a way that always the satisfactory prints, placed in succession in any longitudinal row, are serially numbered, defective prints being neglected. Subsequently, the printed carriers, having passed by another reading instrument, are cut into individual securities, each carrying one print, the defective securities are separated out in a separation device and the remaining, serially numbered individual securities are assembled to form bundles, each having a complete numerical sequence. In this way, a correct and complete numerical sequence of the securities in the bundles is ensured, in spite of the separation of defective securities.
The above approach is however not very adequate from the point of view of production efficiency as the numbering and collecting principle as well as the separation of the defective securities is very time consuming. Another more convenient way to proceed is to number sheets carrying only good prints, sheets having defective prints following a separate route. Entirely defective sheets, i.e. sheets having no good print whatsoever, are destroyed. Partially good sheets can also be destroyed or, more conveniently, be cut into individual securities and processed separately on a single-note numbering machine where only the good securities are numbered in sequence. This approach is preferable from the point of view of optimising the production while still ensuring uninterrupted numerical sequences throughout successive series of securities.
With securities usually printed in arrays on a substrate, several difficulties arise when one wants to build bundles and packs of individual securities which are numbered in sequence. A first problem resides in that each sheet or web segment has to be cut into individual securities. In order to maintain a proper production speed and efficiency, a run of sheets (usually hundred sheets) are piled up and cut together by appropriate cutting devices so as to process the piles into individual bundles of securities. Accordingly, numbering of full sheets has to be carried out so that the numerical sequence remains uninterrupted throughout each bundle. This is ensured by numbering each run of hundred successive sheets so that the serial number at each numbering location on the sheets is incremented or decremented by one unit from the first sheet until the hundredth and last sheet of each run.
Another difficulty arises when one wishes to form packs of bundles while keeping the numerical sequence throughout each pack. Depending on the type of numbering devices used to carry out numbering and on the numbering method used, more or less complex bundle collating systems must be implemented in order to collect and pile the bundles in the appropriate sequence.
In particular, when mechanical numbering devices are used to carry out numbering, which numbering devices can only be actuated in a sequential manner from one numbering iteration to the next as mentioned above, rather complex bundle collating systems must be implemented to collect and store the bundles in the appropriate manner to form packs of bundles with uninterrupted numerical sequence. Such bundle collating systems are for instance described in U.S. Pat. No. 3,939,621, U.S. Pat. No. 4,045,944, U.S. Pat. No. 4,453,707, U.S. Pat. No. 4,558,557, European patent applications Nos. EP 0 656 309, EP 1 607 355, British patent application GB 2 262 729 and International application WO 01/49464.
Depending on the number of securities on each sheet and on the sheet layout, bundle collating can be simplified to some extent. This is for example possible when the number of securities per sheet is a multiple of ten as disclosed in European patent application No. EP 0 598 679. With this solution, a plurality of bundles with consecutive numerical sequences are located within a same stack of sheets, for instance in each column, thus enabling collating of bundles on a column-by-column basis. Nevertheless, with this numbering approach, one still derives several groups of bundles with distinct numerical sequences from each processed stack of sheets (i.e. one sequence per column), and a collating system is therefore still required. In any case, this numbering approach is not applicable to cases where sheets comprise a number of security prints that is not a multiple of ten.
Non-collating numbering approaches which do not require a collating system are known in the art. With such non-collating solutions, numbering of the sheets has to be carried out in a specific manner that depends on the sheet layout, especially the number of security prints per sheet. This particular numbering principle is disclosed in International application No. WO 2004/016433. With such a numbering principle, all bundles derived from a given stack of sheets correspond to one complete consecutive numerical sequence, i.e. a stack of sheets with M×N security prints yields M×N bundles numbered in sequence, that is M×N×100 security papers numbered in sequence. The above numbering scheme enabling non-collating processing of stacks of sheets requires specific numbering devices which are usually more expensive that conventional mechanical numbering devices.
An important issue which is involved in full-sheet numbering processes is accordingly the design and resulting numbering flexibility of the numbering devices used to print the proper serial numbers on each numbering location of the sheets. Numbering devices typically comprise several typographic numbering wheels or disks having alpha-numerical symbols engraved in relief on their circumference, which numbering wheels are actuated by associated mechanical actuating means for rotating the wheels to the appropriate numbering positions.
Besides the usual mechanical numbering devices wherein the numbering wheels are sequentially-actuated, there exists another category of numbering devices which provide more flexibility as to the way the numbering wheels are or can be actuated from one numbering iteration to the next.
A numbering device with freely adjustable numbering wheels is disclosed for example in U.S. Pat. No. 5,660,106, the content of which is incorporated by reference in the present application. This patent discloses a numbering device wherein all the numbering wheels are rotatable about a common driving shaft and are driveable by means of a slip coupling with the driving shaft and wherein electro-magnetically-actuated pawls are provided to selectively block any one of the numbering wheels in the desired position. This numbering device has the advantage that selectively and arbitrary, even non-sequential, numbers can be formed at any time, allowing in particular a non-unitary skip of numbers from one numbering iteration to the next. This numbering device can in particular be used to implement the numbering scheme disclosed in WO 2004/016433. For a detailed explanation of the functioning of this numbering device, reference is made to the entire disclosure of U.S. Pat. No. 5,660,106. Disadvantages of this numbering device however reside in the relatively complex actuation mechanism and related costs, as well as in the build-up of excessive heat caused by friction between the numbering wheels and the common driving shaft.
A somewhat similar but more complicated numbering device than that described in U.S. Pat. No. 5,660,106 is disclosed in German patent application No. DE 30 47 390. One disadvantage thereof resides in the fact that it is slow and only allows rotation of the numbering wheels in one direction.
A hybrid numbering device is disclosed in U.S. Pat. No. 4,677,910, mainly in FIGS. 6 and 6a thereof, the corresponding description being incorporated herein by reference for the sake of explanation. This numbering device partly overcomes the limitation of purely sequential numbering devices by replacing the mechanical numbering wheel for the units digits with a numbering wheel which is kinematically independent from the other numbering wheels and driven by an electric motor. The flexibility of this numbering device is however greatly limited as only one numbering wheel (namely the units wheel only) can be set to any desired position, while the other numbering wheels remain sequentially-actuated.
Another hybrid numbering device is disclosed in International application WO 2004/016433, already mentioned hereinabove and the content of which is incorporated by reference in the present application. In this numbering device, the wheels for the unit digits and ten digits are actuated in a sequential manner (i.e. by purely mechanical actuation means), whereas at least the wheels for the hundred and thousand digits are actuated in an independent manner to allow the skipping of numbers during numbering. This construction allows to carry out the specific numbering process mentioned hereinabove which enables non-collated processing of the bundles.
U.S. Pat. No. 4,843,959 (which corresponds to European patent application EP 0 286 317 A1) discloses, with reference to FIGS. 3 to 6 thereof, another hybrid numbering device in which six numbering wheels out of ten (that is the numbering wheels for the units, tens, hundreds, thousands, ten thousands and hundred thousands) are all driven by respective stepping motors through gearings and shafts. Each motor incorporates a position sensing device, e.g. a shaft encoder for proper control of the operation of the motors, and feedback from the sensing devices to a computer enables the computer to verify the settings of the numbering wheels. The remaining four numbering wheels carry the individual indicia for the prefixes or suffixes, and no description is given regarding the means used to drive said wheels.
One major disadvantage of this solution resides in the fact that a maximum of six numbering wheels, not more, can be driven into rotation by the disclosed arrangement of stepping motors, gearings and shafts.
Another disadvantage resides in the fact that the motors are and can only be located outside the sidewalls of the numbering device, preventing side-by-side use of multiple numbering devices or at least greatly restricting the ability to dispose multiple numbering devices one next to the other in a compact manner, which is particularly critical in the context of full-sheet numbering of securities. Indeed, the six motors are arranged per pairs with the shafts of the motors of each pair facing each other.
Still another problem of the solution described in U.S. Pat. No. 4,843,959 resides in the fact that the gearings used to drive the numbering wheels into rotation all have the same diameter, and that there is accordingly no reduction factor between the motor output and the numbering wheels. In other words, the precision of this numbering device, as well as the rotational speed and torque will be directly dependent on the characteristics of the motor. As stepping motors are used, this in particular implies a very high number of steps per turn for the motor, which translates into motors having very large dimensions that are difficult to integrate within the numbering device itself.
Depending on the number of security prints on each sheet and on the sheet layout, mechanical numbering devices with sequential actuation can be envisaged to carry out numbering according to the numbering scheme of WO 2004/016433. This is again possible only when the number of security prints on each sheet is a multiple of ten (or of twenty-five) and by designing the numbering devices in a specific manner. One such solution is disclosed in International application No. WO 2005/018945. Another alternate solution is disclosed in European patent application 1 731 324 filed on Jun. 8, 2005 in the name of the present Applicant and entitled “NUMBERING PROCESS FOR SECURITIES, METHOD FOR PROCESSING THE NUMBERED SECURITIES AND NUMBERING DEVICE TO CARRY OUT THE NUMBERING PROCESS”. As before, such solutions are not applicable to cases where sheets comprise a number of security prints that is not a multiple of ten or of twenty-five.
A disadvantage of the numbering devices described in U.S. Pat. No. 5,660,106, DE 30 47 390, U.S. Pat. No. 4,677,910, WO 2004/016433, WO 2005/018945, and EP 1 731 324 resides in the fact that, as with conventional mechanical numbering devices, the numbering devices mechanically interact with actuation means that are not part of the numbering devices per se and which are typically mounted on the numbering machine where the numbering device are disposed. In particular, each numbering device requires an actuation cam member for actuating or at least releasing the numbering wheels, which cam member cooperates with a corresponding cam surface placed in the numbering press. In some of the proposed solutions, driving into rotation of the numbering wheels further requires a mechanical coupling, such as the solution described in U.S. Pat. No. 5,660,106 which necessitates a driving gear wheel and an associated toothed segment.